The horizontal distance between the two points is 950m ( starting at 2120m). A vertical line can be drawn from the 1650m point joining it to the horizontal line.
The length of the vertical line will be: 2120 - 1650 = 470
Since we are looking for the direct distance, consider it to be a diagonal line. The horizontal line, the vertical line and the diagonal will make a triangle. The lengths of the first two are already given, therefore we are only required to find the diagonal ( which is also the direct distance). This can be done using the Pythagoras Theorum.
a^2 + b^2 = c^2
950^2 + 470^2 = c^2
1123400 = c^2
square root of 1123400 = c
1059.91 = c (2 dp)